Apparent digestibility of selected feed ingredients for humpback grouper, Cromileptes altivelis

The dry matter (DM), crude protein (CP) and gross energy (GE) apparent digestibility of nine feed ingredients locally available in South Sulawesi were determined with juvenile (similar to 20 g) humpback grouper. In each of the three 4 x 4 latin square experiments, humpback grouper were fed a reference diet and three other diets in which test feed ingredients were substituted at rates of either 40% or 30% for animal or plant sources, respectively. Chromic oxide was used as the indigestible marker. Faeces were collected by sedimentation at 3-h intervals. Each experiment entailed four collection periods with each diet being randomly changed between the tanks. The apparent digestibility of GE could not be determined for three feed ingredients as the amount of collected faeces was insufficient for energy analysis. The derived DM, CP and GE apparent digestibility coefficients (ADC; means +/- S.D.) for the test feed ingredients were, respectively: shrimp head meal-58.5 +/- 3.33, 78.0 +/- 1.32 and 63.6 +/- 0.89; soybean meal-54.8 +/- 2.72, 67.2 +/- 1.29 and 51.1 +/- 0.89; palm oil cake meal-45.3 +/- 2.37, 80.5 +/- 1.30 and 40.4 +/- 3.74; oven-dried blood meal-48.1 +/- 0.85, 55.2 +/- 1.35 and not determined (nd); formic acid-fermented blood meal-67.9 +/- 1.63, 87.5 +/- 0.55 and nd; propionic acid-fernented blood meal-61.7 +/- 2.60, 84.2 +/- 0.69 and nd, local sardine meal-87.2 +/- 2.53, 92.5 +/- 1.40 and 85.2 +/- 0.90; local fish meal-59.1 +/- 1.23, 82.4 +/- 1.99 and 77.2 +/- 1.91; and rice bran meal-22.2 +/- 1.52; 59.5 +/- 1.41 and 44.3 +/- 0.97. The protein of both plant and animal feed ingredients was well digested by humpback grouper, while the DM and GE of the protein-rich animal feed ingredients were more digestible than the carbohydrate-rich plant feed ingredients. (C) 2003 Elsevier Science B.V. All rights reserved.